1. Technical Field
The presently disclosed subject matter relates to vehicle lamps. More particularly, to vehicle lamps which include a light source, a reflector having a parabolic reflective surface configured to reflect light beams, emitted from the light source, as generally parallel reflected light beams, and a lens having a plurality of lens cut portions configured to diffuse the generally parallel light beams coming from the parabolic reflective surface of the reflector. In particular, the presently disclosed subject matter relates to a vehicle signal lamp which can be configured to be capable of easily forming a light distribution pattern, the light distribution pattern having left-right symmetry about the vertical plane that contains the principal optical axis of the vehicle signal lamp as well as up-down symmetry about the horizontal plane that contains the principal optical axis of the vehicle signal lamp.
2. Description of the Related Art
Vehicle signal lamps have been conventionally known which include a light source; a reflector having a parabolic reflective surface configured to reflect light beams, emitted from the light source, as generally parallel reflected light beams; and a lens having a plurality of lens cut portions configured to diffuse the generally parallel light beams coming from the parabolic reflective surface of the reflector. For example, a vehicle signal lamp of this type is disclosed and illustrated in FIGS. 1 and 2 in Japanese Patent Application Laid-Open No. 2001-266614. This signal lamp is shown herein as FIG. 1 and FIG. 2.
The conventional vehicle signal lamp of FIGS. 1 and 2 is configured such that the lens which is generally rectangular in shape is divided by a plurality of vertically extending ridge lines or valley lines into a plurality of lens cut portions. Unless otherwise specified, all the directions or orientations referred to herein are based on those that are defined with the lamp installed in a vehicle. For example, the left and right directions are defined as the directions along the width of the vehicle when viewed from in front of the vehicle, while the longitudinal direction is defined as being consistent with the lengthwise direction of the vehicle, except when referring to a longitudinal axis of a particular object.
More specifically, the conventional vehicle signal lamp allows each of the lens cut portions to diffuse the generally parallel light beams coming from the parabolic reflective surface of the reflector into left and right directions.
The vehicle signal lamp shown in FIGS. 1 and 2 is configured so that the principal optical axis of the vehicle signal lamp (the optical axis of the light source) is not aligned with the center of the generally rectangular lens. Furthermore, with respect to the vertical plane containing the principal optical axis of the vehicle signal lamp (the optical axis of the light source), no mirror image relationship is established between the plurality of lens cut portions on the right side of the vertical plane and the plurality of lens cut portions on the left side thereof.
That is, the vehicle signal lamp disclosed in Japanese Patent Application Laid-Open No. 2001-266614 is configured so that the generally rectangular lens has no left-right symmetry about the vertical plane containing the principal optical axis of the vehicle signal lamp (the optical axis of the light source). It can thus be difficult or impossible to form a light distribution pattern having left-right symmetry.